The Mind Does the Tricks for a Magician

Benedict Carey does a fascinating article on how short cuts that our brains make to assemble our perceptions are exploited by magicians. He describes collaboration between magicians and neuroscientists which have generated a paper in Nature Review Neuroscience. One example:

The visual cortex is attentive to sudden changes in the environment, both when something new appears and when something disappears...A sudden disappearance causes an after-discharge: a ghostly image of the object lingers for a moment...This illusion is behind a spectacular trick by the Great Tomsoni. The magician has an assistant appear on stage in a white dress and tells the audience he will magically change the color of her dress to red. He first does this by shining a red light on her, an obvious ploy that he turns into a joke. Then the red light flicks off, the house lights go on and the now the woman is unmistakably dressed in red. The secret: In the split-second after the red light goes off, the red image lingers in the audience’s brains for about 100 milliseconds, covering the image of the woman. It’s just enough time for the woman’s white dress to be stripped away, revealing a red one underneath.

Anticipation of movement suppresses sensory awareness.

Here is an interesting tidbit...Voss et al. show that the mere expectation of moving a part of our body suppresses that body part's openness to sensory input. Here is the abstract:

When a part of the body moves, the sensation evoked by a probe stimulus to that body part is attenuated. Two mechanisms have been proposed to explain this robust and general effect. First, feedforward motor signals may modulate activity evoked by incoming sensory signals. Second, reafferent sensation from body movements may mask the stimulus. Here we delivered probe stimuli to the right index finger just before a cue which instructed subjects to make left or right index finger movements. When left and right cues were equiprobable, we found attenuation for stimuli to the right index finger just before this finger was cued (and subsequently moved). However, there was no attenuation in the right finger just before the left finger was cued. This result suggests that the movement made in response to the cue caused ‘postdictive’ attenuation of a sensation occurring prior to the cue. In a second experiment, the right cue was more frequent than the left. We now found attenuation in the right index finger even when the left finger was cued and moved. This attenuation linked to a movement that was likely but did not in fact occur, suggests a new expectation-based mechanism, distinct from both feedforward motor signals and postdiction. Our results suggest a new mechanism in motor-sensory interactions in which the motor system tunes the sensory inputs based on expectations about future possible actions that may not, in fact, be implemented.

Brooks on status rules and collectivism

Two recent Op-Ed columns by David Brooks are worth a glance. In the first he argues (one has to admit in a rather superficial and facile manner) that the advent of the iPhone signaled the start of a new era in which the means of transmission has replaced the content of culture as the center of historical excitement and as the marker of social status. He cites this as the third of three epochs of intellectual affectation.

The first, lasting from approximately 1400 to 1965, was the great age of snobbery. Cultural artifacts existed in a hierarchy, with opera and fine art at the top, and stripping at the bottom... This code died sometime in the late 1960s and was replaced by the code of the Higher Eclectica. The old hierarchy of the arts was dismissed as hopelessly reactionary...During this period, status rewards went to the ostentatious cultural omnivores — those who could publicly savor an infinite range of historically hegemonized cultural products.

In his third iPhone era:

...prestige has shifted from the producer of art to the aggregator and the appraiser. Inventors, artists and writers come and go, but buzz is forever. Maximum status goes to the Gladwellian heroes who occupy the convergence points of the Internet infosystem — Web sites like Pitchfork for music, Gizmodo for gadgets, Bookforum for ideas, etc.

The second Brooks essay, which probes the different cognitive styles of Eastern and Western socities, is inspired by the opening ceremony of the Beijing Olympics:

The ceremony drew from China’s long history, but surely the most striking features were the images of thousands of Chinese moving as one — drumming as one, dancing as one, sprinting on precise formations without ever stumbling or colliding. We’ve seen displays of mass conformity before, but this was collectivism of the present — a high-tech vision of the harmonious society performed in the context of China’s miraculous growth...If Asia’s success reopens the debate between individualism and collectivism (which seemed closed after the cold war), then it’s unlikely that the forces of individualism will sweep the field or even gain an edge...For one thing, there are relatively few individualistic societies on earth. For another, the essence of a lot of the latest scientific research is that the Western idea of individual choice is an illusion and the Chinese are right to put first emphasis on social contexts.

Different social attachment styles - different brain structures.

Here is an interesting article arguing that three classic prototypes of attachment style (secure, avoidant, anxious) appear to be regulated by two separate affective dimensions centered on ventral striatum and amygdala circuits, respectively. Here is the abstract, to see the fMRI data showing the relevant structures, follow the link to the article.

Adult attachment style refers to individual personality traits that strongly influence emotional bonds and reactions to social partners. Behavioral research has shown that adult attachment style reflects profound differences in sensitivity to social signals of support or conflict, but the neural substrates underlying such differences remain unsettled. Using functional magnetic resonance imaging (fMRI), we examined how the three classic prototypes of attachment style (secure, avoidant, anxious) modulate brain responses to facial expressions conveying either positive or negative feedback about task performance (either supportive or hostile) in a social game context. Activation of striatum and ventral tegmental area was enhanced to positive feedback signaled by a smiling face, but this was reduced in participants with avoidant attachment, indicating relative impassiveness to social reward. Conversely, a left amygdala response was evoked by angry faces associated with negative feedback, and correlated positively with anxious attachment, suggesting an increased sensitivity to social punishment. Secure attachment showed mirror effects in striatum and amygdala, but no other specific correlate. These results reveal a critical role for brain systems implicated in reward and threat processing in the biological underpinnings of adult attachment style, and provide new support to psychological models that have postulated two separate affective dimensions to explain these individual differences, centered on the ventral striatum and amygdala circuits, respectively. These findings also demonstrate that brain responses to face expressions are not driven by facial features alone but determined by the personal significance of expressions in current social context. By linking fundamental psychosocial dimensions of adult attachment with brain function, our results do not only corroborate their biological bases but also help understand their impact on behavior.

The emerging web Leviathan - paranoia over search and content

I thought I would pass on this interesting piece in the New York Times business section on yet more controversy surrounding Google, this time over its emergence as a company that provides not only search results but also original content. I use its two main content subsidiaries: Blogger (to host this blog) and YouTube (the top video site). Now Knol comes along,a potential competitor with Wikipedia, a place where experts can share their knowledge on a variety of topics. The article points out: "Google’s growing reach into the content business could create conflicts similar to those faced by Microsoft in its dual role as a provider of an operating system that others run their software applications on and a maker of applications."

Right hemisphere more involved in self recognition of body parts.

Hemispheric asymmetries in self and other body parts recognition is examined by Frassinetti et al., by comparing how healthy patients, and patients with left and right hemisphere brain damage perform in visual matching experiments involving body parts. Their abstract:

The aim of this study was to investigate whether the recognition of "self body parts" is independent from the recognition of other people's body parts. If this is the case, the ability to recognize "self body parts" should be selectively impaired after lesion involving specific brain areas. To verify this hypothesis, patients with lesion of the right (right brain-damaged [RBD]) or left (left brain-damaged [LBD]) hemisphere and healthy subjects were submitted to a visual matching-to-sample task in two experiments. In the first experiment, stimuli depicted their own body parts or other people's body parts. In the second experiment, stimuli depicted parts of three categories: objects, bodies, and faces. In both experiments, participants were required to decide which of two vertically aligned images (the upper or the lower one) matched the central target stimulus. The results showed that the task indirectly tapped into bodily self-processing mechanisms, in that both LBD patients and normal subjects performed the task better when they visually matched their own, as compared to others', body parts. In contrast, RBD patients did not show such an advantage for self body parts. Moreover, they were more impaired than LBD patients and normal subjects when visually matching their own body parts, whereas this difference was not evident in performing the task with other people's body parts. RBD patients' performance for the other stimulus categories (face, body, object), although worse than LBD patients' and normal subjects' performance, was comparable across categories. These findings suggest that the right hemisphere may be involved in the recognition of self body parts, through a fronto-parietal network.

Circuits that switch fear ON and OFF

Sah and Westbrook write a brief review of work by Herry et al. and Likhtik et al. Here are some mixed and edited clips:

The work pinpoints the neural circuits that mediate the bidirectional transition between a defensive behaviour — fear — and the default exploratory behaviour. These functions are evolutionarily old, and their dysfunction is thought to underlie a host of anxiety disorders in humans, including post-traumatic stress and panic disorder

To study the neural mechanisms that mediate fear responses, fear conditioning is widely used. In a typical procedure, animals are exposed to a normally harmless stimulus (such as a sound or light) before a brief exposure to an aversive stimulus — typically a foot shock. A few such rounds of pairing the harmless (conditioned) stimulus with the aversive (unconditioned) stimulus create an association between them in the animals' minds...It is important to study how fear is first learned. However, the pertinent question for clinicians is how fear can be eliminated or reduced. Extinction of fear occurs when the association between the conditioned and the unconditioned stimuli is broken by repeated presentations of the conditioned stimulus only. But does the association get completely erased from the memory? The answer is no. Although the conditioned stimulus eventually fails to elicit fear responses, much, if not all, of the original learned fear survives extinction. So when the extinguished conditioned stimulus is tested either during, or shortly after, exposure to a dangerous context again, the conditioned fear is renewed spontaneously. Extinction therefore involves new learning, and its activation by situational cues inhibits the expression of fear responses to the conditioned stimulus.

During fear conditioning, convergence of inputs from the conditioned stimulus (CS) and unconditioned stimulus (US) to fear neurons in the basolateral amygdala (BLA) leads to potentiation of the conditioned input and activation by the CS of neurons in the central nucleus (CEA) that initiates physiological and behavioural responses characteristic of fear. b, During extinction, inputs from the medial prefrontal cortex (PFC) activate neurons in the intercalated cell masses (ICMs) — either directly or through activation of extinction neurons in the basolateral amygdala — which then inhibit the activity of fear output neurons in the CEA. c, During fear renewal, inputs from the hippocampus, which evaluates the current context, activate inhibitory interneurons in the basolateral amygdala that silence extinction neurons, thus restoring fear responses.

Noninvasive Brain Stimulation Improves Language Learning

Here are some interesting results from Flöel et al. :

Anodal transcranial direct current stimulation (tDCS) is a reliable technique to improve motor learning. We here wanted to test its potential to enhance associative verbal learning, a skill crucial for both acquiring new languages in healthy individuals and for language reacquisition after stroke-induced aphasia. We applied tDCS (20 min, 1 mA) over the posterior part of the left peri-sylvian area of 19 young right-handed individuals while subjects acquired a miniature lexicon of 30 novel object names. Every subject participated in one session of anodal tDCS, one session of cathodal tDCS, and one sham session in a randomized and double-blinded design with three parallel versions of the miniature lexicon. Outcome measures were learning speed and learning success at the end of each session, and the transfer to the subjects' native language after the respective stimulation. With anodal stimulation, subjects showed faster and better associative learning as compared to sham stimulation. Mood ratings, reaction times, and response styles were comparable between stimulation conditions. Our results demonstrate that anodal tDCS is a promising technique to enhance language learning in healthy adults and may also have the potential to improve language reacquisition after stroke.

Frontal Cortex: unconscious inhibitory control

An interesting study from van Gaal et al. I give the abstract, followed by a figure describing the experimental procedure:

To further our understanding of the function of conscious experience we need to know which cognitive processes require awareness and which do not. Here, we show that an unconscious stimulus can trigger inhibitory control processes, commonly ascribed to conscious control mechanisms. We combined the metacontrast masking paradigm and the Go/No-Go paradigm to study whether unconscious No-Go signals can actively trigger high-level inhibitory control processes, strongly associated with the prefrontal cortex (PFC). Behaviorally, unconscious No-Go signals sometimes triggered response inhibition to the level of complete response termination and yielded a slow down in the speed of responses that were not inhibited. Electroencephalographic recordings showed that unconscious No-Go signals elicit two neural events: (1) an early occipital event and (2) a frontocentral event somewhat later in time. The first neural event represents the visual encoding of the unconscious No-Go stimulus, and is also present in a control experiment where the masked stimulus has no behavioral relevance. The second event is unique to the Go/No-Go experiment, and shows the subsequent implementation of inhibitory control in the PFC. The size of the frontal activity pattern correlated highly with the impact of unconscious No-Go signals on subsequent behavior. We conclude that unconscious stimuli can influence whether a task will be performed or interrupted, and thus exert a form of cognitive control. These findings challenge traditional views concerning the proposed relationship between awareness and cognitive control and stretch the alleged limits and depth of unconscious information processing.

Here is the procedure. SOA is the stimulus-onset asynchrony, the interval between the onsets of the two stimuli. (I wish these people would remind us what these jargon abbreviations mean, so I don't have go look them up to remind myself. )

Stimuli and trial timing of the masked Go/No-Go task and the control experiment. The gray circle and black cross duration was 16.7 ms. Go signal duration was 100 ms. In conscious No-Go trials, the SOA between the No-Go signal and the Go signal was 83 ms. Participants had to respond to the Go signal (black metacontrast mask) but were instructed to withhold their response when a No-Go signal preceded the Go signal. In the masked Go/No-Go task, a gray circle served as a No-Go signal, whereas in the control experiment, the No-Go signal was a black cross. Therefore, the masked gray circle was associated with inhibition in the masked Go/No-Go task and thus served as an unconscious No-Go signal. In the control experiment, the unconscious gray circle was not associated with inhibition (and was task irrelevant) because participants were instructed to inhibit their responses on a black cross. Comparing processing of unconscious gray circles between both experiments enabled us to test whether (1) high-level inhibitory control processes can be triggered unconsciously, (2) unconscious No-Go signals reach prefrontal areas, and (3) task relevance influences the depth of processing of unconscious stimuli.

Music for the week... Ode to Joy

My daughter sent me this gem...

MindBlog at the Chicago Art Institue

Lunch today in the Garden Restaurant at the Art Institute of Chicago, part of my annual summer ritual, which also includes the Halstead Street Days street fair in Boystown. (Click to enlarge picture).

Culture-sensitive neural substrates of human cognition.

Han and Northoff write a perspective piece in which they aim to show how the relatively novel approach of transcultural neuroimaging can bridge the gap between neuroscientific investigations of supposedly culture-invariant neural mechanisms and psychological evidence of culture-sensitive cognition. They collect and summarize a variety of neuroimaging data in summary figures. Below is the abstract, and PDF is here.

Our brains and minds are shaped by our experiences, which mainly occur in the context of the culture in which we develop and live. Although psychologists have provided abundant evidence for diversity of human cognition and behaviour across cultures, the question of whether the neural correlates of human cognition are also culture-dependent is often not considered by neuroscientists. However, recent transcultural neuroimaging studies have demonstrated that one's cultural background can influence the neural activity that underlies both high- and low-level cognitive functions. The findings provide a novel approach by which to distinguish culture-sensitive from culture-invariant neural mechanisms of human cognition.

Behavioral therapy can reverse chronic fatigue syndrome and increase prefrontal volume

Another example of a therapy that induces brain plasticity, this work from de Lange et al. , carried out with women, since chronic fatigue syndrome predominantly affects women. Here is a clip describing the therapy, followed by the abstract of the paper.

During cognitive behavioral therapy (CBT), fatigue-related cognitions were challenged to diminish somatic attributions, to improve sense of control over symptoms and to facilitate behavioral changes. In parallel, a structured physical activity program was implemented. Furthermore, a work rehabilitation schedule was drawn up in order to realize a gradual work reentry. Final sessions of CBT dealt with relapse prevention and further improvement of self-control.

Chronic fatigue syndrome (CFS) is a disabling disorder, characterized by persistent or relapsing fatigue. Recent studies have detected a decrease in cortical grey matter volume in patients with CFS, but it is unclear whether this cerebral atrophy constitutes a cause or a consequence of the disease. Cognitive behavioural therapy (CBT) is an effective behavioural intervention for CFS, which combines a rehabilitative approach of a graded increase in physical activity with a psychological approach that addresses thoughts and beliefs about CFS which may impair recovery. Here, we test the hypothesis that cerebral atrophy may be a reversible state that can ameliorate with successful CBT. We have quantified cerebral structural changes in 22 CFS patients that underwent CBT and 22 healthy control participants. At baseline, CFS patients had significantly lower grey matter volume than healthy control participants. CBT intervention led to a significant improvement in health status, physical activity and cognitive performance. Crucially, CFS patients showed a significant increase in grey matter volume, localized in the lateral prefrontal cortex. This change in cerebral volume was related to improvements in cognitive speed in the CFS patients. Our findings indicate that the cerebral atrophy associated with CFS is partially reversed after effective CBT. This result provides an example of macroscopic cortical plasticity in the adult human brain, demonstrating a surprisingly dynamic relation between behavioural state and cerebral anatomy. Furthermore, our results reveal a possible neurobiological substrate of psychotherapeutic treatment.

Mental imagergy induces cortical reorganization that reduces phantom limb pain

The journal Brain offers an interesting open access article by MacIver et al. on the use of mental imagery to reduce phantom limb pain. They used a mindfulness-based ‘body-scan’ meditation technique as a means of achieving a relaxed state, based on a pain management technique developed by Kabat-Zinn et al. This remarkably simple technique of imagining movement and sensation in the missing limb resulted in significant pain relief. All subjects found learning the body scan useful as a means of relaxation, regardless of whether their pain lessened, and they all felt that the body scan was a useful facilitator to imagining the return of the phantom limb. I give the abstract here, with apologies for not taking the time to translate it into more friendly prose.

Using functional MRI (fMRI) we investigated 13 upper limb amputees with phantom limb pain (PLP) during hand and lip movement, before and after intensive 6-week training in mental imagery. Prior to training, activation elicited during lip purse showed evidence of cortical reorganization of motor (M1) and somatosensory (S1) cortices, expanding from lip area to hand area, which correlated with pain scores. In addition, during imagined movement of the phantom hand, and executed movement of the intact hand, group maps demonstrated activation not only in bilateral M1 and S1 hand area, but also lip area, showing a two-way process of reorganization. In healthy participants, activation during lip purse and imagined and executed movement of the non-dominant hand was confined to the respective cortical representation areas only. Following training, patients reported a significant reduction in intensity and unpleasantness of constant pain and exacerbations, with a corresponding elimination of cortical reorganization. Post hoc analyses showed that intensity of constant pain, but not exacerbations, correlated with reduction in cortical reorganization. The results of this study add to our current understanding of the pathophysiology of PLP, underlining the reversibility of neuroplastic changes in this patient population while offering a novel, simple method of pain relief.

Sexual orientation - basis in brain structure and function

Swaab offers a useful brief review of this topic (PDF here) with a complete list of references.

Genetics of political behaviors - molecular level

I wanted to bring into a separate post the comment by James Fowler on the post below mentioning his work. "We do have some papers that go to the molecular level, associating drd2, drd4, maoa, and 5htt with various political behaviors. One of these papers has just been published in Journal of Politics, and all of these papers are all available at my website
http://jhfowler.ucsd.edu."

Your nose, and your bored brain...

From today's Science NYTimes: An article by Natalie Angier on the emotional clout of smells and the curious fact that smell cues most frequently evoke thoughts of early childhood, under the age of 10 (this certainly has been my experience.) Also, an article by Benedict Carey on the creative aspects of boredome.

A new perspective on the genetic basis of brain diseases

An article by Nicholas Wade notes the emergence of a new view on the genetic basis of brain diseases like schizophrenia (see also article by Sands in Nature). There has been a presumption that we looked hard enough, we would find an ensemble of genes whose mutations typically correlated with a disease. The search for common variants in schizophrenia has largely drawn a blank, suggesting that natural selection has done its job in keeping them at bay (after all, reproductive success is compromised in schizophrenics). A view is emerging that the genetic component of the disease may be due to a large number of variants, each of which is very rare (mainly deletions of DNA segments), rather than to a handful of common variants. According to this new idea, schizophrenia continues to appear because it is driven by a spate of new mutations that occur all the time in the population. The new landscape might complicate development of genetic diagnostics for schizophrenia, but not necessarily of therapies based on understanding the underlying mechanisms of the disease.

Gender differences in math performance...

... don't exist for children in grades 2 to 11, according according to a massive statistical analysis carried out by Hyde et al. on data provided through school reporting on the No Child Left Behind federal program (PDF here) - although there is slightly more male variability in scores.

The theologians, the neurologists, and God

Here is the PDF of a review by Alasdair Coles in a recent issue of Brain of a series of recent books that evaluate contributions of neurobiology to the understanding of the relationships between brain, psyche and God. He reviews the history of such efforts starting with Pascal, William James, and others.